Turbo-generators have been proposed to produce power for electrical devices. A traditional turbo-generator system consists of a discrete turbine and a discrete generator which are coupled via a shaft. The turbine is used to convert momentum from a fluid stream into rotary motion. The shaft transmits the motion to the generator rotor, which typically contains permanent magnets or coil windings around each of its poles. Stator poles are typically arranged around the perimeter of the generator rotor, each of which is wrapped with coil windings The perimeter of the rotor is completely surrounded by stator poles to maximize energy conversion.
Variations of this design include the switched reluctance generator, in which the rotor has no permanent magnets or windings yet is still coupled to the turbine via a shaft, and several versions of a dual-purpose rotor design in which a single component functions as both the turbine and the generator rotor, having windings surrounding each of its poles or permanent magnets at the tips of each of its poles. In the latter case, because the stator poles surround the rotor, the fluid must be directed axially, rather than tangentially, through the turbine.
However, due to size constraints, these designs lead to limited use in portable electronic devices. Consequently, a need exists for a compact turbo-generator device capable of producing power for portable electronic devices.